I actually have a 2 kVA 12V Outback inverter and 800 Ah of SLA batteries (badly sulfated down to 200 Ah, but I am now slowly recovering their capacity). While I can certainly build such an arrangement using the parts I have and some additional safety equipment, I have to say that I think SunnyBoy has done some things that Enphase never has (to my knowledge). Specifically, rather than simply dropping off in a grid overfrequency event, the SunnyBoy inverters linearly reduce their output power as you increase the frequency of the source above around 60.5 Hz. This is particularly attractive to grid operators since these inverters will gradually reduce their generation in an oversupply event.

This also allows a clever control scheme that the Sunny Island inverters take advantage of to allow their grid-connected inverters to run islanded. I assume their TL SunnyBoy units use a similar scheme.

Since the SolarEdge inverters control the optimizers directly, I suppose they use their own methods for modulating PV production.

Unfortunately, to my knowledge, Enphase microinverters do not seem to have any concept beyond "harvest as much energy as possible". The underlying assumption being that the grid can accept whatever electricity the microinverters can produce. This makes operation of such an AC-coupled system with Enphase microinverters somewhat "fiddly".

Frankly, I'm more inclined to simply use my LEAF and/or SLA batteries with 12V inverter(s) to ride out a storm unless there was a long-term outage. Then I might consider trying to use my Outback Inverter to bring the PV array into service.

It would be nice if Enphase would make using the PV in a backup situation easier. One simple solution would be to create a mode for the inverters which matches the SunnyBoy output power versus frequency curve to allow use of Enphase inverters with a Sunny Island inverter. I guess there is no chance of that since it violates the NIV principle (Not Invented Here).

I suspect there will be something coming from Enphase fairly soon now that they have bi-directional inverters, AC batteries and advanced control schemes available with their Envoy-S.

Yeah, I have to think they are working on solving this issue as it would be silly to not when you are making an ecosystem like this. I'm hoping it's just that they want to get their main marketing use case going first, TOU shifting, and then backup power will come next.

I think the only thing you can do for our generation of models is create different profiles so that some shut off sooner than others so you can have a few levels of load/charging before all the microinverters shut down leaving you on just battery power until they start coming back online again and the cycle repeats. It should work well enough and be all automatic. During peak production you could also shut down some of the microinverter circuits to help keep the production down.

I bought a generator and converted it to tri fuel after buying the LEAF 5 years ago and have yet to actually have a use for it so It seems my local grid is stable enough that I'm not likely to ever get the itch to setup a way to use the solar power without the grid but it sure would be s fun project.

Isn't one of the features of Enphase's "Grid Optimization Services", relying on 5th gen Enphase S-inverters, that they can coordinate inverter behavior in regards to voltage, real and reactive power on some sort of near-real-time basis? Is that just marketing for future features? Beyond the basic grid profiles that exist today.

ltbighorn wrote:Isn't one of the features of Enphase's "Grid Optimization Services", relying on 5th gen Enphase S-inverters, that they can coordinate inverter behavior in regards to voltage, real and reactive power on some sort of near-real-time basis? Is that just marketing for future features? Beyond the basic grid profiles that exist today.

Enphase inverters are current sources, not voltage sources. The new S-series units can provide leading or lagging current to the grid, but none of them can act like a voltage source. As such, I do not believe Enphase offers any way to create an island with their current product line.